1. Technical Field
The present invention relates to an actuator and an optical scanner.
2. Related Art
As actuators, an actuator which uses a torsional vibrator is suggested (for example, refer to JP-A-2010-79243).
For example, in JP-A-2010-79243, an optical deflector is disclosed which includes a movable plate (movable portion), a support frame (support portion), and a pair of elastic support portions (connecting portion) which torsionally and rotatably (swingably) supports the movable plate with respect to the support frame and in which each elastic support portion is configured of two rods (beam member).
The movable plate, the support frame, and the pair of elastic support portions are integrally formed by anisotropically etching a silicon substrate in which the principal surface is configured of a (100) plane of silicon.
Moreover, in the optical deflector according to JP-A-2010-79243, the movable plate is octagonal in plan view. In the movable plate having the shape in plan view, a weight of the movable plate at a position separated from a rotation (swing) axis is smaller, and there is an advantage in that a moment of inertia is decreased.
However, when the movable plate in which the shape in plan view is octagonal is manufactured by using the anisotropic etching described above, variation in the shape is increased due to a relationship with the crystal plane.